Self-centering guide



June 18, 1968 M, H, HUMBERT 1 3,388,507

sELF-CENTERING GUIDE Filed July 23, 1965 ATTORNEY United States Patent O 3,388,507 SELF-CENTERING GUIDE Marvin H. Humbert, Cedar Rapids, Iowa, assignor to The Cedar Rapids Engineering Co., Inc., Cedar Rapids, Iowa, a corporation of Iowa Filed July 23, 1965, Ser. No. 474,336 Claims. (Cl. 51-262) ABSTRACT OF THE DISCLOSURE A guide for a valve seat grinder which centers in the least worn portion of the valve guide and which has a sleeve with a slow external taper and a faster internal taper and a tapered pin received in the sleeve to expand it and lock it into the valve guide.

This invention relates in general to guides and, in particular, to a self-centering guide for a valve seat grinder.

Internal combustion engines have inlet and exhaust valves which operate in valve seats to allow gases to pass into and out of the engines. After long use the valve seats must be ground concentric With the valve guide to provide a tight seal with the valves. Since the valve stems are continually working in the valve guides, the guides become worn and bell-shaped and it becomes diicult to accurately position a valve seat grinding tool relative to the center of the valve guide.

It is an object of the present invention to provide a guide for a valve seat grinding tool which centers in the least portion of the valve guide to provide accurate positioning of the tool.

Another object is to provide an improved grinding tool guide.

Yet another object is to provide a grinding guide that can be used in valve guides of different sizes.

A feature of this invention is found in the provision for a grinding guide formed with a split sleeve with a slow taper on its outer surface and a faster taper on its inner surface and a tapered pin receivable through the sleeve and formed with a faster taper to expand the sleeve and lock the assembly in the substantially unwom portion of a valve guide.

Further features, objects and advantages will become apparent from the following description and claims when read in view ofthe drawings, in which:

FIGURE l is a sectional View showing the guide in place in an engine,

FIGURE 2 is a sectional view of the sleeve,

FIGURE 3 is a view of the tapered pin; and,

FIGURE 4 shows the pin and sleeve in various positions.

FIGURE l illustrates an engine formed with a valve seat 11 which it is desired to grind. A valve guide opening 12 has ends 13 and 14 which have been worn by movement of the valve stern, not shown. The valves of the engine are removed to allow grinding.

A grinding guide 16 comprises the present invention and consists of a split sleeve 17 and a tapered pin 18.

The sleeve 17 is best shown in FIGURE 2. It is formed with a first plurality of slots 19 cut into the sleeve from a first end 21 and a second plurality of slots 22 formed in the sleeve from the second end 23 to allow the sleeve 3,388,507 Patented June 18, 1968 ice to ilex. The sleeve is formed with a slow taper on its outer surface 24 of about 0.0007 inch per inch, for example. Thus, the sleeves outer diameter is slightly smaller at end 23 than it is at end 21.

The inside diameter of sleeve 17 is also tapered as, for example, 0.25 inch per foot with a larger diameter at end 21 than end 23.

Tapered pin 18 is best shown in FIGURE 3. It has a tapered portion 27 which is longer than sleeve 17 and which has a taper of 0.25 inch per foot being larger at portion 28 than end 29. The diameter of pin 27 is such that it tits into sleeve 17. An upper portion 32 of pin 18 is concentric with portion 27 and is adapted to receive a hollow grinder thereon and is formed with a transverse opening 34, adjacent its upper end 33.

FIGURE 4 illustrates the sleeve 17 and pin 18 in the assembled relationship. The pin is inserted through the sleeve and a clip spring 31 is placed in a groove formed in pin 18 near end 29 to prevent the pin from being withdrawn from sleeve 17.

Since the inner taper of sleeve 17 matches the outer taper of pin 27 the members t together along their lengths and the pin 27 can expand the sleeve to enlarge it due to the slots 19 and 22. The clip spring 31 limits the upward motion of pin 18 relative to the sleeve, but the pin can move longitudinally through the sleeve to various positions as shown in dotted line in FIGURE 4.

FIGURE l illustrates a guide with this invention in use. The pin 18 is positioned relative to sleeve 17 until clip 31 rests against end 23 of the sleeve.

This gives sleeve 17 its minimum diameter. The assembly is then dropped into guide hole 12, lifted slightly and then pushed downwardly with a slight turning motion. This seats the grinding guide in the smallest portion of the hole 12 which is the least worn part of the hole and the portion will center the valve. Thus, grinding will be referenced to the least worn portion of the valve guide which assures accurate grinding.

The slow taper on the outside of sleeve 17 assures intimate contact with the hole over a long length at the center portion of the hole rather than at the worn portions 13 and 14 as occurs in prior guide devices.

After grinding has been accomplished the pin and sleeve is pulled by inserting a pin through opening 34 and lifting. The pin will move relative to the sleeve thus allowing it to contract and be easily removed. Spring 31 prevents the sleeve from remaining in the hole.

A number of sleeves of diterent outside diameters may be used with the same pin 18 by merely removing spring 31, and changing a first sleeve 17 for a second one of different outside diameters and then replacing spring 31. This allows the guide to operate in holes 12 of diierent diameters.

It is seen that this invention provides a centering guide which centers in the least worn portions of valve guide holes and although it has been described with respect to a preferred embodiment it is not to be so limited as changes and modilications may be made which are within the full intended scope as defined by the appended claims.

I claim:

1. A guide device for aligning a valve seat grinding device in an engine having a valve guide hole comprising, a ilexible sleeve formed with a slow external taper and a faster internal taper received in the valve guide hole, a tapered pin formed with a faster taper received within the exible sleeve to expand it and lock the pin and sleeve to the engine in the valve guide hole, and an extension attached to the pin to receive the valve seat grinding device thereon.

2. In apparatus according to claim 1 wherein the flexible cylinder is formed of metal which has been slotted from opposite ends to render it flexible.

3. In apparatus according to claim 1 a stop means attached to the end of the pin to prevent the pin from being removed from the sleeve.

4. In apparatus according to claim 1 wherein the slow external taper is in the range from 0.01 to 0.0001 inch per inch.

5. In apparatus according to clairn 1 wherein the faster taper is in the range of 0.5 to 0.1 inch per foot.

References Cited UNITED STATES PATENTS 1 JAMES L. JONES, JR., Primary Examiner.

ROBERT C. RIORDON, Examiner.

J. A. MATHEWS, Assistant Examiner. 

